Most solar panels that convert the sun's radiation into electric energy use fixed flat-panels of silicon. Silicon is the photovoltaic material of choice because its properties are well known and it is cheap, readily available in the quantities needed, durable and reliable. Silicon is also a single-junction photovoltaic material so it is not affected by changes in the spectral distribution; its output depends on the integrated power density within the limits of its absorption range. Flat panels of silicon are simple to make and install in an outdoor environment.
There are disadvantages to fixed, flat silicon solar panels. Silicon has a relatively low conversion efficiency, typically 18% to 20% and theoretically not to exceed 30%. Because of this relatively low conversion efficiency, bigger panels, more panels and a larger area for the panels are used to produce power than would be the case were the conversion efficiency higher. In the case of roof-mounted solar panels for home electricity generation, the amount of power used by a household is usually much more than can be generated by solar power from flat silicon panels given the size of the roof of a residence. In the case of power plants, land requirements for solar collectors quickly become the dominant cost. Finally, most solar panels are made overseas so supplies of new and replacement panels may be subject to international stability issues and currency fluctuations.
One way to increase the conversion efficiency of flat silicon panels is to have them track the sun. While solar panel tracking systems do improve efficiency, they also add to capital cost, operating costs, and maintenance costs. They also use electrical power to operate thereby offsetting their conversion efficiency gains. Furthermore, their tracking ability is compromised by wind and gravitational deflection.
The efficiency of solar panels may also be improved by different photovoltaic materials, although better photovoltaic materials are more expensive and not widely available.
Despite the challenges of solar electricity, a solar panel that would be capable of producing more electricity per square meter would be of significant advantage over current solar panels and useful in more numerous applications.